Add support for Qt5 to qspatialite provider.

The detachFromResultSet() changes in qsql_spatialite.{cpp,h} are taken
from https://code.qt.io/cgit/qt/qtbase.git/commit/?id=fc15a1d5e2cb064d
by Mark Brand <mabrand@mabrand.nl>.

Additionally the sqlite3 & sqlite3_stmt types need to be declared as
opaque pointers per http://doc.qt.io/qt-5/qmetatype.html#Q_DECLARE_METATYPE

For Qt5 Q_PLUGIN_METADATA() should be used instead of Q_EXPORT_PLUGIN2()
per http://doc.qt.io/qt-5/qtquick-porting-qt5.html#qml-plugins

src/providers/spatialite/qspatialite/qsql_spatialite.cpp

@@ -60,6 +60,10 @@
 #include <sqlite3.h>
 #include <qgsslconnect.h>
 
+#if QT_VERSION >= 0x050000
+Q_DECLARE_OPAQUE_POINTER(sqlite3*)
+Q_DECLARE_OPAQUE_POINTER(sqlite3_stmt*)
+#endif
 Q_DECLARE_METATYPE(sqlite3*)
 Q_DECLARE_METATYPE(sqlite3_stmt*)
 
@@ -325,10 +329,12 @@ QSpatiaLiteResult::~QSpatiaLiteResult()
 void QSpatiaLiteResult::virtual_hook(int id, void *data)
 {
     switch (id) {
+#if QT_VERSION < 0x050000
     case QSqlResult::DetachFromResultSet:
         if (d->stmt)
             sqlite3_reset(d->stmt);
         break;
+#endif
     default:
         QSqlCachedResult::virtual_hook(id, data);
     }
@@ -485,6 +491,14 @@ QSqlRecord QSpatiaLiteResult::record() const
     return d->rInf;
 }
 
+#if QT_VERSION >= 0x050000
+void QSpatiaLiteResult::detachFromResultSet()
+{
+    if (d->stmt)
+        sqlite3_reset(d->stmt);
+}
+#endif
+
 QVariant QSpatiaLiteResult::handle() const
 {
     return QVariant::fromValue(d->stmt);

src/providers/spatialite/qspatialite/qsql_spatialite.h

@@ -80,6 +80,9 @@ class QSpatiaLiteResult : public QSqlCachedResult
     int numRowsAffected();
     QVariant lastInsertId() const;
     QSqlRecord record() const;
+#if QT_VERSION >= 0x050000
+    void detachFromResultSet();
+#endif
     void virtual_hook(int id, void *data);
 
 private:

src/providers/spatialite/qspatialite/smain.cpp

@@ -47,6 +47,9 @@ QT_BEGIN_NAMESPACE
 
 class QSpatiaLiteDriverPlugin : public QSqlDriverPlugin
 {
+#if QT_VERSION >= 0x050000
+    Q_PLUGIN_METADATA(IID "org.qgis.QSpatiaLiteDriverPlugin")
+#endif
 public:
     QSpatiaLiteDriverPlugin();
 
@@ -75,7 +78,9 @@ QStringList QSpatiaLiteDriverPlugin::keys() const
     return l;
 }
 
+#if QT_VERSION < 0x050000
 Q_EXPORT_STATIC_PLUGIN(QSpatiaLiteDriverPlugin)
 Q_EXPORT_PLUGIN2(qspatialite, QSpatiaLiteDriverPlugin)
+#endif
 
 QT_END_NAMESPACE